No abstract

In order to endow water‐based polyurethane with special functionality, vegetable oil‐based waterborne polyurethane with self‐healing properties is synthesized. Firstly, soybean oil‐based emulsifier (GA‐ESO) was prepared by epoxy soybean oil and glutaric acid without solvent and catalyst. Then, two Diels−Alder (DA) diols were prepared by the DA reaction between N,N′‐(4,4′‐methyldiphenyl) bismaleimide, 4‐maleimide phenol and furfuryl alcohol, respectively. Finally, GA‐ESO and DA diols used as the raw material was reacted with isophorone diisocyanate to synthesize a series of soybean oil‐based waterborne polyurethane with self‐healing behavior. The effects of DA diol on the properties of polyurethane films and the self‐healing process and mechanism of polyurethane membrane were investigated. The results showed that after the addition of DA diol, the particle size of polyurethane emulsion increased from 28.8 to 85.3 nm, the tensile strength was improved from 0.3 to 12.6 MPa, and the water contact angle was enhanced from 68.5° to 84.2°. In addition, it can be observed that with the addition of DAdiol, the polyurethane film had self‐healing behavior at high temperature, and the highest self‐healing efficiency can reach 100%.

A series of soybean oil-based polyols were synthesized via the reaction between epoxidized soybean oil and 1,3-propanediol, trimethylolpropane and xylitol, respectively. The aqueous polyurethanes were synthesized by prepared soybean oil-based polyols. The effect of hydroxyl value of soybean oil-based polyols on the mechanical, thermal, hydrophobic properties of the aqueous polyurethane films were also investigated. The results showed that the OH value of polyol increased, the T g of aqueous polyurethane films increased from 30.04 to 88.28 C and the water contact angle of materials improved from 80.80 to 98.20 . Besides, water absorption reduced from 40.25% to 2.40%. Also, all samples were placed in the 1 wt% sodium hydroxide solution at 45 C to test the degradation behaviors. After 24 h, the results demonstrated that aqueous polyurethane synthesized by the highest hydroxyl value (251.00mgKOH/g)polyol had the lowest degradation rate(7.10%). Finally, the mechanical properties and morphology of the aqueous polyurethane film after degradation were investigated, which proved that the hydroxyl value affected the mechanical properties and morphology of the aqueous polyurethane film after degradation.